For those who boat in areas that have reliable cell coverage, go to your APP Store and get one of the many AIS Apps. Marine Traffic is there and loads quickly, but is not real time. The one I use combines good navigation charts with AIS, and is Real Time, all for a low annual fee, though unless you leave it on, you may want one that loads more quickly.
When I leave cell service, unless I have my phone as a hot spot, I get charts where there is GPS, but no AIS information.
As it is on my phone, I have it with me wherever I go. A few days ago I used it to navigate on a shoreside walk in Honolulu, far from my boat.